RFR: 8323672: Suppress unwanted autoconf added flags in CC and CXX [v7]

[Magnus Ihse Bursie]

On Thu, 18 Jan 2024 16:21:46 GMT, Julian Waters <jwaters at openjdk.org> wrote:

>> [JDK-8323008](https://bugs.openjdk.org/browse/JDK-8323008) reports unwanted autoconf flags being added to the command line, and solves the issue by filtering out the added flags by force. This is not optimal however, as doing so leaves the autoconf message that the flags were added still displaying during the configure process, which is confusing. Instead, setting a couple of fields to disable the autoconf internals responsible for the unwanted flag is a cleaner solution
>
> Julian Waters has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Implement custom AC_PROG_CC and AC_PROG_CXX in util.m4

I agree with Erik, this looks interesting. I also like the benefit of transparency that it brings, breaking down the black box of autoconf a bit more. 

In contrast with Erik I'm not so worried about future breakage. Autoconf has basically stalled in development since decades. If someone were to pick up development again (like what happened with GNU Make) we will surely see signs of activity long before this breaks. And if that happens, we can just file a bug on autoconf instead of trying to work around the broken behaviour, right? 🤷 

I would like to take this PR for a spin on a bunch of machines/environments, though, to see that it does not fail obviously on any of them.

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PR Comment: https://git.openjdk.org/jdk/pull/17401#issuecomment-1900497417